E46 Braking Issue

[Hamsterdam]

I've got a issue with the brakes on my E46, have to push the pedal very hard to bring the car to a complete stop.

Took it to my local garage, the brakes and discs were fine but they replaced the brake fluid. This made a difference for a few days but the issue is back, almost as bad a before.

Any ideas?

[SebringMan]

Diesel or petrol?

It could be anything. To rule out of the obvious does the pedal creep down if you do the following?

1) With the engine off pump the brake pedal until it goes hard and rises up ; keep your foot pressed on the brake pedal
2) Start the engine, still keeping your foot on the brake pedal
3) If the pedal doesn't go down the chances are the following.

-You either have a shot servo
-A vacuum leak is present going from the engine to the servo
-The servo check valve is shot ; partly the above.

[Hamsterdam]

It's a 318 petrol.

It's going to BMW on Thursday to replace the drivers airbag due to a recall so I was going to ask them. I'm a bit pissed off that my usual decent garage thought it was just a brake fluid issue.

[SebringMan]

I have just re-read your first post. Part of me wonders if it's down to stuck pad and/or sliders.

Unfortunately I've seen a few garages and even specialists who should know better balls this up. It tends to be:

-Stuck sliders ; but you'd have a slightly spongy pedal ; copper grease on these never helps
-Corrosion or stuck dirt on the brake pad contact areas; If they cannot move this will also make a difference.

[helix402]

Maybe brake pipes near the fuel tank are rusting away.

[Hamsterdam]

I'll see what BMW say. I'll mention it to them when dropping it off. Kind of scary when the car doesn't stop completely.

Thanks for your input guys

[Elliot2000]

On 318's oil can go through the vac pump and then through the pipe to the servo - eventually causes loss of servo and a hard brake pedal

U can pop the pipe off the bottom of the servo to see if the is any oil residue

[Hamsterdam]

Confirmed that it is the brake Servo. The garage I've used for years want £600 for the job.

[helix402]

Run away. Get a used eBay servo. If it needs a vacuum pump too, same again-but strip and rebuild it first with new seals.

[Deskdumper]

Did this fix the fault. I have a 318 petrol auto.

Scary when you cant stop.

[iSore]

The problem isn't the servo, it's the brake vacuum pump on the back of the head. They fail and cannot generate any vacuum causing really heavy brakes.